[Hack&Lube]

Stupid question, I've got a bench in the basement and I'm afraid to try for a 1 rep max because I'm usually alone without spotter but here's the silly thing...do I count the bar?

I have some old totally cast iron bar or something from my uncle from the 70s. It weighs 40-45 lbs (minus rust). With that bar and 75 lbs of weights I can usually do 10-11 reps easily in a slightly inclined position.

When I try those 1 rep max calculators online, I add the bar and I end up with 120 lbs. I add in the 10 reps and it gives me a 1 rep max of 160 lbs. Now I'm 5'9 and weigh a measly 145. Does that mean I'm already benching over my body weight? This doesn't seem right to me at all.

I have absolutely no weightlifting experience or workout knowledge whatsoever btw, I just goto the basement every now and then when I'm bored or feeling self-conscious. I'm a scrawny kid who was never good at this stuff and I'm sick of being scrawny. What's the best way to do this? Continue what I have now but more reps?